Circuit Opening Relay

Circuit opening relay controls the fuel pump circuit. When EFI main relay is energized, EFI main relay provides battery voltage to circuit opening relay. When engine is cranking and start signal is delivered to Engine Control Module (ECM), the circuit opening relay ground circuit is grounded at ECM terminal FC. Circuit opening relay then provides voltage to fuel pump for fuel pump operation. When start signal is released and engine is running, the ECM then uses engine speed input signal for controlling the ground circuit for circuit opening relay and provides voltage to fuel pump for fuel pump operation.